Semiconductor device and a method of manufacturing the same

ABSTRACT

Upon the manufacture of a non-leaded type semiconductor device having an encapsulater, and a gate cured resin and air vent cured resins which remain as a result of the exposure of leads and tub-suspension leads to a mounting surface of the encapsulater and the formation of the encapsulater, a groove through which a resin flows is not provided over the full circumference of a cavity defined in a mold die for forming the encapsulater. A gate and air vents are provided outside an area in which no groove is defined. The flow of the resin between the cavity and each of the gate and air vents is made through a gap or space defined between each of the adjacent leads and each tub-suspension lead. If the leads and the tub-suspension leads are cut at a groove-free place, then the occurrence of resin waste and a resin crack can be restrained because the gate cured resin and the air vent cured resins have their surfaces which are flat and level with the leads and the tub-suspension leads.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 09/920,942 filedAug. 3, 2001 now abandoned.

FIELD OF THE INVENTION

The present invention relates to a technology for manufacturing a resinmolded or encapsulation type semiconductor device using a lead frame,and particularly to a technology effective for application to themanufacture of a semiconductor device wherein external electrodeterminals (leads) are exposed to the mounting surface side as in an SON(Small Outline Non-Leaded Package) and a QFN (Quad Flat Non-LeadedPackage).

BACKGROUND OF THE INVENTION

A resin encapsulation type semiconductor device makes use of a leadframe upon its manufacture. The lead frame is fabricated by forming ametal plate as a desired pattern by punching using a precision press oretching. The lead frame has a support portion called a “tub or the like”for fixing a semiconductor chip, and a plurality of leads whose leadingends (internal ends) face the periphery of the support portion. The tubis supported by tub-suspension leads which extend from a frame portionof the lead frame.

When the resin encapsulation type semiconductor device is fabricatedthrough the use of such a lead frame, the semiconductor chip is fixed tothe tub of the lead frame, and electrodes of the semiconductor chip andleading ends of the leads are connected to one another by conductivewires. Afterwards, the lead internal-end side including the wires andthe semiconductor chip is sealed with an insulating resin to therebyform an encapsulater (package). Further, an unnecessary lead frameportion is removed by cutting, and the leads and tub-suspension leadsprotruding from the package are cut. Each of the leads is brought to aflat state or processed into a predetermined shape.

As technologies for solving a problem as to a transfer mold for forminga resin encapsulation package, there are known technologies described inUnexamined Patent Publication Nos. Hei 5(1993)-326799, 2000-61989 andHei 5(1993)-299455, for example.

Although a resin injection hole (gate) is not illustrated in the drawingin the above technologies, the prior art set forth as a premise hasdescribed that the resin injection hole is provided in a lower mold.Accordingly, a resin (called “gate cured resin”) cured at a gate portionextends on one surface side of a lead frame so as to have apredetermined height.

Unexamined Patent Publication No. 2000-61989 has disclosed thetechnology of separating a runner from a molded plastic package withbeing flush with the package upon a transfer mold process. Namely, atransfer mold die has a movable gate lowered so as to make contact withthe plastic package formed at a resin inlet for the cavity on the sameplane as the plastic package before the resin is cured after having beeninjected in the cavity. Accordingly, the runner can be cut on a flushbasis with the plastic package.

The same reference has described that when the resin cured within therunner is removed, the resin cured at the runner portion remains at eachedge of the plastic package, and a bottleneck is produced in thesubsequent lead formation and trimming process due to such a remainder.Problems will be quoted from the same reference and described below.

(1) Damage is put on the trimming of each lead and the formation of adie, and manufacturing yields and a production throughput are reduced.It is necessary to repair or fix up an expensive die.

(2) There is a possibility that upon lead trimming and formingprocesses, the plastic package will be peeled off from the lead frame,thereby causing a problem about the reliability of a completed product.

(3) The adhesion of the remainder or remaining materials to the plasticpackage as it is will lead to a serious result. Described typically, acheck is made to respective packages and all the remaining materials aremanually removed. Therefore, personnel costs increase and amanufacturing throughput is reduced.

According to the present technology, runner's fragments are not leftbehind with being attached to the plastic package even after thetransfer mold. Further, the runner can be detached from the molded leadframe. Thus the work of manually removing the remainder becomesunnecessary. It is also possible to avoid damage to the trimming of eachlead and a lead forming instrument due to the remainder as well as toavoid damage to a packaged semiconductor device.

The present technology shows the technical idea that since the remainderof the resin produces a bottleneck in the trimming process such as thebending of each lead, the occurrence of the remainder in the lead frameis avoided even after the removal of the runner. The present technologyhas no description about the cutting of leads at a gate portion, i.e., abasal portion of the package and makes little mention of such a problem.

Unexamined Patent Publication No. Hei 5(1993)-299455 describes thetechnology of thinning a gate in stepped form in advance at a base of aresin encapsulated portion so that when a resin portion cured at a gateportion for forming the resin molded portion is separated from apackage, a gate residual is not much left on a placed piece or fragment,and causing a gate cured resin to remain on the placed piece thinner orshorter upon removal of the gate cured resin.

The present technology does not show the idea of cutting aplaced-fragment portion causing the remainder of the gate.

On the other hand, as one resin encapsulation type semiconductor devicefabricated using a lead frame, there is known a non-leaded typesemiconductor device such as an SON, a QFN or the like adopted or takenas a semiconductor device structure wherein one surface of the leadframe is single-sided molded to thereby form a package, and leadscorresponding to external electrode terminals are exposed to themounting surface side of the package, thereby avoiding the intentionalprotrusion of the leads from the peripheral surface of the package.

SUMMARY OF THE INVENTION

In terms of a size reduction in semiconductor device, the prevention ofbending of leads corresponding to external electrode terminals, etc., anon-leaded type semiconductor device such as a single-sided molded SONor QFN has been used.

Since the outer shape of the non-leaded type semiconductor device isprincipally determined depending on a resin encapsulater (package) and alead cutting castle or castled extension formed on its periphery, thesemiconductor device can be reduced in size as compared with asemiconductor device of such a type that leads are placed on theperiphery of a package, generally called a “QFP (Quad Flat Package)” oran SOP (Small Outline Package)”. The lead cutting castle or castleextension is produced by ensuring an area for applying a die between acutting-plane line and a package when the leads are cut by punches, andis formed with a width of about 0.1 mm in the embodiment of the presentspecification, for example.

Problems about the manufacture of the conventional single-sided moldednon-leaded type semiconductor device will now be explained.

A description will first be made of one in which a resin encapsulater(package) is formed on one surface side of a lead frame by a transfermold with the manufacture of QFN as an example.

FIG. 31 is a plan view showing a resin encapsulater formed by a transfermold and a unit lead frame pattern. As shown in the same drawing, a leadframe 1 has a structure having a frame portion 2 shaped in the form of arectangular frame, a plurality of leads 3 extending inwardly from insidethe respective sides of the frame portion 2, and tub-suspension leads 4(only one tub-suspension lead is shown in the drawing) whichrespectively extend inwardly of the frame portion from the four cornersof the frame portion 2 and support a central tub (not shown). A resinencapsulater (package) 5 is formed in a central portion of a unit leadframe pattern 6, and leading end portions (internal end portions) of therespective leads 3 extend within the package 5. Lower surfaces of theleads 3 are exposed from the package 5. The exposed lead portions serveas external electrode terminals for surface mounting when asemiconductor device is brought about.

Although not illustrated in the drawing, a semiconductor chip fixed ontothe tub is placed within the package 5. Further, electrodes of thesemiconductor chip and inner ends of the leads 3 are electricallyconnected to one another by conductive wires.

Upon a transfer mold, a gate (G) is located in one corner (correspondingto the upper right corner in FIG. 31) of the lead frame 1. A resin isinjected into a cavity of a mold die through the gate to thereby formthe corresponding package 5. At this time, air lying within the cavityescapes from air vents (E) located in the remaining three corners of thelead frame 1 to the outside of the mold die. Thus, the resin enters eventhe gate and the air vents and hence the resin at these portions is alsocured by resin's curing. The resin cured at the gate portion will bereferred to as a “gate cured resin 7” below. The resins cured at the airvent portions will be called “air vent cured resins 9”.

The package 5 shaped in rectangular form is generally chamfered as shownin FIG. 31 to have slopes B in such a way as to avoid the presence ofcornered portions (corners). The slopes 8 are large in gate portion andsmall in air vent portions.

After the transfer mold, the resin cured inside each runner for guidingthe resin is removed when the curing of the resin is finished. FIG. 31shows a state in which a runner cured resin or the like is removed andis a diagram showing that the gate cured resin 7 and the air vent curedresins 9 remain.

FIG. 32 is a side view typically showing the lead frame 1, package 5,air vent cured resins 9, runner cured resin 10 and gate cured resin 7.FIG. 33 is a typical cross-sectional view showing the lead frame 1,tub-suspension leads 4, package 5 and gate cured resin 7 or the like. Asshown in FIG. 32, the resin cured at the gate portion upon removal ofthe runner cured resin 10 is formed integrally with the package 5.Therefore, the resin will break in the course thereof and a gate curedresin 7 of a chevron or mounting type as viewed from the side remains.Namely, as the gate cured resin 7 is kept away from the package 5, thethickness thereof becomes thick and its leading end is brought to abroken state.

Thus, even when the gate cured resin 7 is set to such a shape that itsthickness becomes thick as it is distant from the package, and isdesigned in such a manner that the gate cure resin is preferably brokenin the vicinity of the package upon breakage and removal of the gatecured resin, the gate cured resin cannot be prevented perfectly fromremaining, and the size and shape of the produced remaining cured resinare made in various ways.

As shown in FIG. 33, the cured resins remain on both sides of thetub-suspension lead 4 as indicated by dots. Namely, upon the transfermold, spaces defined by parting surfaces of upper and lower molds of amold die and the tub-suspension lead 4 and leads 3 adjacent thereto bothlocated at the gate portion are formed as spaces which communicate withthe gate. The cured resins having entered the spaces correspond to thecured resin portions indicted by the dots. These cured resin portionsare generally called resin burrs 11. The thickness of each resin burr 11is identical to that of each lead 3 in a state in which the partingsurfaces of the upper and lower molds of the mold die are closely bondedto the obverse and reverse sides of the lead frame.

However, when a gap is defined between each of the parting surfaces andthe lead frame where the above package is clamped between the partingsurfaces of the upper and lower molds of the mold die and the leadframe, the resin enters into the gap and so-called resin flashes occurin each lead surface or the like. In the resin-flash generated state,the thickness of each resin burr 11 becomes thicker than that of eachlead.

After the transfer mold, the leads 3 and tub-suspension leads 4 bothprotruding from the periphery of the package are cut at the peripheraledge of the package 5, whereby the corresponding non-leaded typesemiconductor device (QFN) is manufactured. When, at this time, thesizes of the gate cured resin 7 and each air vent cured resin 9 are toolarge to accommodate or hold them in the lead cutting castle, the gatecured resin 7 and the air vent cured resins 9 are also cut upon leadcutting.

FIG. 34 is a typical view showing the situation in which a gate curedresin 7 and air vent cured resins 9 are cut by a die 15 and punches 16together with each tub-suspension lead 4. The cutting of leads 3 is alsocarried out by a die and punches each having a similar structure.

However, when the gate cured resin 7 remains at one side of a package asshown in FIG. 34, it is essential that the gate cured resin 7 is cutwhile the die 15 is being applied to the mounting surface side contraryto the normal lead cutting. This is because since the flatness of eachlead surface on the package side is lost due to the presence of the gatecured resins 7, and the remaining amounts thereof are all different, thedie 15 cannot be stably applied to each lead.

It turned out that since the gate cured resin 7 takes such a shape as toprotrude toward its corresponding punch 16 as described above, the gatecured resin 7 firstly contacts the punch 16 and thereby stress isapplied to the punch 16 upon cutting as shown in FIG. 35, wherebybreakage, cracks and chipping are developed therein by stressconcentration and resin waste is frequently produced.

It has been found that the resin waste 17 is spattered over theperiphery and is thereby attached not only to other lead frame portionsbut also to surfaces related to the cutting of the die 15 and punches 16and cut surfaces of the gate cured resin 7 and tub-suspension lead 4 asshown in FIG. 34. Namely, the resin waste is produced by (1) cuttingaway the resin in fine form when the punches are applied to the gatecured resins as described above and (2) rubbing the punches and theircut surfaces against each other when the punches are returned to theirpredetermined positions after their cutting. Further, the resin wastedrops out even by vibrations at the carrying of a product, contaminatesa cutting die and is re-attached to other product portions.

In the non-leaded type semiconductor device, there is a fear that sinceeach lead surface exposed to the back of the package is brought to theexternal electrode terminal surface so as to serve as a mountingsurface, an electrically-isolated state occurs in a mounted state whenthe insulative resin waste is attached or crimped to the surface,thereby interfering with a stable operation of the semiconductor device.

When the gate cured resin is much cracked upon its cutting, a crackenters even into the package, thereby causing a reduction in moistureresistance and degradation of reliability.

If a method of applying the die 15 to the mounting surface side of eachlead with a cutting-plane line interposed therebetween and cutting theleads by the punches 16 from the side opposite to the mounting surfaceis adopted as shown in FIG. 34, then cut burrs occur in the mountingsurface of each lead, thereby losing the flatness of the mountingsurface and degrading reliability.

A non-leaded type semiconductor device has heretofore been fabricatedaccording to a method shown by such a flowchart as shown in FIG. 36. Thenon-leaded type semiconductor device is manufactured via respectiveprocess steps of Steps 201 through 207. Namely, after the commencementof work, the semiconductor device is fabricated via the respectiveprocess steps of chip bonding (S201), wire bonding (S202), molding(S203), gate pre-cutting (S204), plating (S205), pinch-cut by compositecut molding (S206), and lead tip cutting (S207), and thereafter the workis finished.

In the present manufacturing method, the gate pre-cutting (S204) iscarried out before the plating step, and each gate-portiontub-suspension lead is punched out to a predetermined length. Therefore,even if resin waste occurs, the resin waste is removed by cleaningcorresponding to processing subsequent to the plating. Thus, a problemabout the above-described resin waste little arises.

However, the present manufacturing method is accompanied by a drawbackthat as a cutting process executed by a press machine, the gatepre-cutting (S204), the pinch-cut (S206) by composite cut molding, andthe lead tip cutting (S207) are carried out twice, thereby increasingthe manufacturing cost of a semiconductor device.

Thus the present applicant adopts a manufacturing method of achieving areduction in manufacturing cost with the press machine-based cuttingprocess as one. FIG. 37 is a flowchart using the present manufacturingmethod.

A non-leaded type semiconductor device is manufactured via respectiveprocess steps of Steps 301 through 307. Namely, after the commencementof work, the semiconductor device is fabricated via the respectiveprocess steps of chip bonding (S301), wire bonding (S302), molding(S303), plating (S304), gate crush by composite cut molding (S305),pinch-cut (S306) and lead tip cutting (S307), and thereafter the work iscompleted.

A composite cut mold is attached to one press machine. Underintermittent motion of a lead frame and a cutting operation based oncomposite cut molding, the cutting (corresponding to the gate crush forcutting one point in linear form) of a gate portion and tub-suspensionleads thereof, pinch-cutting for cutting remaining tub-suspension leadsused to support a package, and lead tip cutting for cutting all theleads at the basal portion of the package are executed to complete asemiconductor device, and thereafter the work is finished.

FIGS. 38(a) and 38(b) are respectively typical views showing a gatecrush operation. In a manufacturing method using gate crush, processingis done in a state in which a package 5 is placed on a lower surface ofa lead frame 1.

Namely, a die 15 is placed on the upper side of the lead frame 1. Apunch 16 goes up from its lower side to cut a gate cured resin 7 andeach tub-suspension lead 4 extending together with the gate cured resin7. The punch 16 serves like a knife edge without having a structure forcutting them to a predetermined length and simply cuts the gate curedresin 7 and each tub-suspension lead 4. The tub-suspension lead 4 isbent as shown in FIG. 38(a) under the post-cut moving operation of thepunch 16. Resin waste 17 is produced even upon the cutting of the gatecured resin 7 and the tub-suspension lead 4.

Owing to the execution of such gate crush processing, the cutting of thegate cured resin and each tub-suspension lead thereat at pinch-cutting(S306) become unnecessary, and the produced amount of resin waste can bereduced. An advantage is brought about in that it is possible to reducea resin crack produced in the gate portion and a cut failure intub-suspension lead.

However, it has been found that in the case of the present gate crush,the cut resin surface and the die are rubbed against each other when thecut type (die) is opened as shown in FIG. 38(b), so that resin waste isspattered, thereby causing adhesion to each lead surface. An arrow inFIG. 38(b) is used to indicate the situation in which the resin waste 17is spattered upon die opening to thereby adhere onto each lead (whilethe lead corresponds to the tub-suspension lead in the drawing,unillustrated leads are also arranged on this surface of the package 5).

An object of the present invention is to provide a technology whereinwhen a gate cured resin and air vent cured resins are cut upon themanufacture of a non-leaded type semiconductor device fabricated by asingle-sided mold, resin waste is restrained from occurring to therebyprevent the attachment of the resin waste to external electrodeterminals.

Another object of the present invention is to provide a technologywherein when a gate cured resin and air vent cured resins are cut uponthe manufacture of a non-leaded type semiconductor device fabricated bya single-sided mold, a resin crack is retrained from occurring tothereby prevent a reduction in moisture resistance of the semiconductordevice and the occurrence of a failure in outward appearance thereof.

The above, other objects and novel features of the present inventionwill become apparent from the description of the present specificationand the accompanying drawings.

Summaries of typical ones of the inventions disclosed in the presentapplication will be described in brief as follows:

(1) There is provided a semiconductor device which has an encapsulatercomprising an insulating resin, leads and tub-suspension leads exposedto a mounting surface of said encapsulater and a gate cured resin andair vent cured resins which remain as a result to form saidencapsulater, and wherein each of the gate cured resin and the air ventcured resins exists in a portion between each tub-suspension lead andeach lead with a thickness identical to or smaller than the thickness ofeach of resin burrs.

Such a semiconductor device is manufactured by the followingmanufacturing method.

There is provided a method of manufacturing a semiconductor device,comprising a step for preparing a lead frame having a frame portion, aplurality of leads which protrude inwardly of the frame portion from theframe portion, and a plurality of tub-suspension leads which protrudeinwardly of the frame portion from the frame portion and support a tubat leading end portions thereof; a step for fixing a semiconductor chipto one surface of the tub; a step for electrically connecting electrodesof the semiconductor chip and the leads; a step for covering thesemiconductor chip and the leads with an encapsulater comprising aninsulating resin and exposing the leads and the tub-suspension leads toa mounting surface of the encapsulater; and a step for cutting the leadsand the tub-suspension leads; and wherein a vertical space defined byonly the sides of the leads and the tub-suspension leads is used as aresin flow path to form the encapsulater, and the leads and thetub-suspension leads are cut at a resin portion cured in the verticalspace defined by only the sides of the leads and the tub-suspensionleads.

Further, a gate provided in a mold die is provided outside the verticalspace defined by only the sides of the leads and the tub-suspensionleads, and a resin passes through the gate and flows through thevertical space to thereby form the encapsulater. In addition, air ventsdefined in the mold die are provided outside the vertical space definedby only the sides of the leads and the tub-suspension leads, and theresin passes through the vertical space and goes through the air vents.

According to the means of (1) referred to above,

(a) The cutting of leads and tub-suspension leads that protrude from theperiphery of an encapsulater (package), and the cutting of gate curedresins and air vent cured resins produced upon the formation of thepackage are performed at portions respectively identical in thicknessand whose front and back are flat. Thus, they can be cut by punches anda die without partly applying an on-cutting stress on the gate curedresins and air vent cured resins in a large way. It is thereforepossible to reduce the occurrence of resin waste to a large extent ascompared with the conventional cutting method and restrain theoccurrence of a resin crack.

(b) Since the resin waste can be restrained from occurring, theattachment and crimping of the resin waste to lead surfaces serving asexternal electrode terminals due to the spattering of the resin waste,and the occurrence of flaws caused by the crimping can be restrained. Itis also possible to ensure solderability at mounting and enhancemounting yields. Furthermore, the reliability of the mounting orimplementation of a non-leaded type semiconductor device can beimproved.

(c) Since a matrix type lead frame takes a structure wherein unit leadframe patterns are vertically and horizontally arranged in line, theprevention of the spattering of the resin waste results in theprevention of contamination of the resin waste on each unit lead framepattern around a predetermined unit lead frame pattern, wherebyproduction yields can be improved to a great extent.

(d) Since the occurrence of the resin waste can be restrained, thecontamination caused by the cut-die's resin waste can be prevented fromoccurring, and the availability factor of a press machine for mounting acut die can be improved.

(e) Since the gate cured resins and air vent cured resins around thepackage are rendered integral with resin burrs between adjacent leads orthose between tub-suspension leads and leads and are identical to theresin burrs in obverse and reverse sides, it is difficult to visuallyconfirm the gate cured resins and air vent cured resins on the peripheryof the package of the non-leaded type semiconductor device. Thus, thesemiconductor device is look good and preferable even in outerappearance, and increases in commodity property.

(f) The manufacturing cost of a semiconductor device can be reduced interms of productivity and an improvement in yield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a typical plan view, and

FIG. 1(b) a cross-sectional view taken along line A—A of FIG. 1(a),showing a lead frame portion single-sided molded by a method ofmanufacturing a semiconductor device according to one embodiment (firstembodiment) of the present invention;

FIG. 2 is a front view illustrating the semiconductor device accordingto the first embodiment;

FIG. 3 is a plan view depicting the semiconductor device according tothe first embodiment;

FIG. 4 is a bottom view showing the semiconductor device according tothe first embodiment;

FIG. 5 is a cross-sectional view taken along line B—B of FIG. 3;

FIG. 6 is a cross-sectional view taken along line C—C of FIG. 3;

FIG. 7 is a cross-sectional view showing the state of mounting of thesemiconductor device according to the first embodiment;

FIG. 8 is a flowchart for describing the method of manufacturing thesemiconductor device according to the first embodiment;

FIG. 9 is a plan view showing a lead frame employed in the manufacturingmethod of the semiconductor device according to the first embodiment;

FIG. 10 is a plan view depicting a unit lead frame pattern portion ofthe lead frame;

FIG. 11 is a plan view showing a state in which a semiconductor chip isfixed to the lead frame, and electrodes of the semiconductor chip andlead inner ends are connected to one another by wires in accordance withthe manufacturing method of the semiconductor device according to thefirst embodiment;

FIG. 12 is a plan view illustrating a state in which a package is formedon one surface of the lead frame by means of a single-sided mold inaccordance with the manufacturing method of the semiconductor deviceaccording to the first embodiment;

FIG. 13 is a cross-sectional view showing a state in which a package isformed on one surface of a lead frame in accordance with themanufacturing method of the semiconductor device according to the firstembodiment;

FIG. 14 is a plan view illustrating the correlation between a cavity, aresin flow passage or path and a lead frame formed in the single-sidedmold by a mold die;

FIG. 15 is a plan view showing a lead frame formed by cuttingtub-suspension leads and a gate cured resin or an air vent cured resinplaced on both sides of the tub-suspension leads in accordance with themanufacturing method of the semiconductor device according to the firstembodiment;

FIG. 16 is a typical view illustrating a state in which the gate curedresin or the like is cut;

FIG. 17 is a typical plan view showing a cutting die for cutting thegate cured resin or the like;

FIG. 18 is a typical cross-sectional view depicting the cutting die forcutting the gate cured resin or the like:

FIG. 19 is a plan view showing the lead frame from which leads extendingalong an X direction are cut in accordance with the manufacturing methodof the semiconductor device according to the first embodiment;

FIG. 20 is a typical view illustrating a state in which the leadsextending along the x direction are cut;

FIG. 21 is a typical plan view depicting a cutting die for cutting theleads extending along the X direction;

FIG. 22 is a plan view showing a semiconductor device obtained bycutting leads extending along a Y direction in accordance with themanufacturing method of the semiconductor device according to the firstembodiment, and a remaining lead frame portion;

FIG. 23 is a typical view illustrating a state in which the leadsextending along the Y direction are cut;

FIG. 24 is a typical plan view depicting a cutting die for cutting theleads extending along the Y direction;

FIG. 25 is a cross-sectional view showing another semiconductor devicemanufactured by using a flat lead frame wherein leads, a tub andtub-suspension leads are disposed on the same plane in the firstembodiment;

FIG. 26 is a bottom view of another semiconductor device shown in FIG.25;

FIG. 27 is a typical cross-sectional view illustrating a transfer moldstate obtained according to a method of manufacturing a semiconductordevice showing another embodiment (second embodiment) of the presentinvention;

FIG. 28 is a typical plan view showing a lead frame single-sided moldedin accordance with the method of manufacturing the semiconductor deviceaccording to the second embodiment;

FIG. 29 is a typical cross-sectional view illustrating a state in whicha gate cured resin and an air vent cured resin, and tub-suspension leadsoverlapping with these are cut in accordance with the method ofmanufacturing the semiconductor device according to the secondembodiment;

FIG. 30(a) and FIG. 30(b) are typical plan views showing a lead frameportion single-sided molded by a method of manufacturing a semiconductordevice according to a further embodiment (third embodiment) of thepresent invention;

FIG. 31 is a plan view illustrating a conventional lead frame in which apackage is formed on one surface thereof by a transfer mold;

FIG. 32 is a typical side view depicting the lead frame;

FIG. 33 is a typical cross-sectional view showing a gate cured resin,resin burrs, etc. of the lead frame;

FIG. 34 is a typical view showing a state in which a conventionaltub-suspension lead, and a gate cured resin and an air vent cured resinoverlapping with the tub-suspension lead are cut;

FIG. 35 is a typical view illustrating a state in which the conventionaltub-suspension lead and the gate cured resin overlapping with thetub-suspension lead are cut;

FIG. 36 is a flowchart for describing a method of manufacturing aconventional non-leaded type semiconductor device;

FIG. 37 is a flowchart for describing a method of manufacturing anon-leaded type semiconductor device including a gate crush processstep; and

FIG. 38(a) and FIG. 38(b) are typical views illustrating the gate crushoperation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will hereinafter bedescribed in detail with reference to the accompanying drawings.Incidentally, ones each having the same function are respectivelyidentified by the same reference numerals in all the drawings fordescribing the embodiments of the present invention, and theirrepetitive description will therefore be omitted.

First Embodiment

FIGS. 1 through 24 are respectively diagrams related to a method ofmanufacturing a semiconductor device showing one embodiment (firstembodiment) of the present invention.

QFN showing one example of a non-leaded type semiconductor devicemanufactured by the method of manufacturing the semiconductor deviceshowing the first embodiment will first be explained. FIG. 2 is a frontview of the semiconductor device, FIG. 3 is a plan view thereof, FIG. 4is a bottom view thereof, FIG. 5 is a cross-sectional view taken alongline B—B of FIG. 3, and FIG. 6 is a cross-sectional view taken alongline C—C of FIG. 3, respectively.

In the QFN type semiconductor device 20, a sealing body or encapsulater(insulating sealing body: package) 5 comprises a flat quadrangular orsquare body (rectangular body) as shown in FIGS. 2 through 4. Angularportions (corners) of the sealing body 5 is chamfered to form slopes 8.One of the slopes 8 is large and serves as a resin injection point orportion through which a resin is injected, upon formation of the package5. Other three slopes 8 become small and serve as air vent portions fromwhich air escapes upon formation of the package 5.

As shown in FIGS. 2, 5 and 6, the package 5 has sides which respectivelyserve as inclined surfaces formed so as to be easy to come off or escapefrom a mold die when the package 5 is formed by a transfer mold method.Accordingly, an upper surface 22 of the package 5 is smaller than thesize of a mounting surface 21 formed as a lower surface even in the caseof any of the drawings referred to above.

Leads 3 are exposed from the reverse side or back of the package 5,i.e., the peripheral edges of the mounting surface 21. The leads 3 aredisposed at its respective sides at predetermined pitches, for example.The four corners of the package 5, i.e., tub-suspension leads 4 areexposed at or from the peripheral edges of the mounting surface 21,which are associated with the respective centers of the slopes 8.

As shown in FIGS. 5 and 6, the leads 3 and 4 slightly protrude outsidefrom a rising edge 5 a of the package 5 with respect to the surfaces ofthe leads 3 and tub-suspension leads 4, which are covered with thepackage 5, i.e., covered surfaces 3 a and 4 a. This serves as areceiving portion of a die upon cutting the leads 3 and thetub-suspension leads 4 and is less than or equal to 0.1 mm, for example.While resin burrs 11 exist between the respective leads 3 and betweenthe tub-suspension leads 4 and the leads 3, the resin burrs 11 are alsocut by the die and punch. Therefore, the edges of the resin burrs 11 andthe leading edges or tips of the leads 3 and tub-suspension leads 4 arelinearly formed without irregularities at the peripheral edge of thepackage 5.

On the other hand, when a transfer mold is used to form the package 5,the resin enters or pours into any of the resin injection portion andair vent portions, and they are cured upon a resin curing process,whereby a gate cured resin 7 and an air vent cured resin 9 are formed.

While the resin injection portion (gate: G) is described later in thesemiconductor device manufacturing method in the first embodiment, it isformed by a space (equivalent to a vertical space corresponding to thelead 3 and the tub-suspension lead 4) between the tub-suspension lead 4and the leads 3 disposed on both sides thereof over a predeterminedlength (a) at the edge portion of the package 5 as shown in FIGS. 1(a)and 1(b). This is defined as a space which does not extend out beyondthe thickness of the tub-suspension lead 4 and that of the lead 3. Thus,the thickness of the resin cured at the gate portion having the length(a), i.e., the thickness of the gate cured resin 7 coincides with thethickness of the lead 3 or the tub-suspension lead 4 or smaller thanthat thereof. The thickness of the gate cured resin 7 becomes identicalto that of each resin burr 11 formed between the adjacent leads 3.Therefore, the front and back sides thereof are both brought to flatsurfaces respectively. Since the leads 3 and the tub-suspension leads 4are cut within a region for the length (a), a trace of the gate curedresin 7 is not prominent as compared with the resin burrs 11 in thesemiconductor device 20 of the first embodiment 1 while it is designatedat reference numeral 7 in FIGS. 3 and 1(a).

Since, however, a gate groove or trench is provided outside the length(a) as a groove in the mold die, the gate cured resin 7 protrudesoutside the length (a) beyond the thickness of the lead 3 in a state inwhich the lead frame 1 shown in FIGS. 1(a) and 1(b) is shown. The gatecured resin 7 takes such a shape as being placed on a frame portion.Taking such a shape makes it possible to sufficiently ensure thecross-sectional area of a gate.

In a manner similar to the gate portion even in the case of air ventportions (E), each air vent is formed by a space between thetub-suspension lead 4 and the leads 3 disposed on both sides thereofover a predetermined length (b) as viewed from the edge of the package5. This is defined as a space which does not extend out beyond thethickness of the tub-suspension lead 4 and that of the lead 3. Thus, thethickness of the resin cured at the portion having the length (b), i.e.,the thickness of the air vent cured resin 9 coincides with the thicknessof the lead 3 or the tub-suspension lead 4 or smaller than that thereof.The thickness of the air vent cured resin 9 becomes identical to that ofeach resin burr 11 formed between the adjacent leads 3. Therefore, thefront and back sides thereof are both brought to flat surfacesrespectively. As a result, a trace of the air vent cured resin 9 is notprominent as compared with the resin burrs 11 while being designated atnumerals 9 in FIG. 3 and FIG. 1(a) in the semiconductor device 20according to the first embodiment. However, since each air vent isprovided outside the length (b) as a groove in the mold die, the airvent cured resin 9 distinctly exists on the leads in a state in whichthe lead frame 1 shown in FIGS. 1(a) and 1(b) is shown.

As shown in FIGS. 5 and 6, the semiconductor device 20 has a tub 25within the package 5. A semiconductor chip 27 is fixed to itscorresponding upper surface of the tub 25 with a jointing material 26interposed therebetween. The tub 25 is smaller than the semiconductorchip 27. The tub 25 has a structure where it is supported by the fourtub-suspension leads 4. Namely, the tub 25 and the tub-suspension leads4 are integrally formed.

Unillustrated electrodes formed on the surface of the semiconductor chip27, and inner ends of the leads 3 are respectively electricallyconnected to one another by conductive wires 28. The tub 25,semiconductor chip 27, and the wires 28 a are placed within the package5. The means for electrically connecting the electrodes of thesemiconductor chip 27 and the leads 3 respectively may take anotherconfiguration.

When the tub-suspension leads 4 are used as external electrodeterminals, the ground electrode of the semiconductor chip 27 and thetub-suspension leads 4 may be connected to one another by the wires 28.

FIG. 7 is a cross-sectional view showing the mounting of a semiconductordevice 20 on a wiring board or substrate 29. Lands 30 are provided onone surface of the wiring board 29 in association with leads 3 andtub-suspension leads 4 which serve as external electrode terminals ofthe semiconductor device 20. Further, the leads 3 and the tub-suspensionleads 4, which serve as the external electrode terminals of thesemiconductor device 20, are respectively superimposed on these lands 30and electrically connected thereto with a bonding or jointing material31 interposed therebetween.

A description will next be made of a specific manufacture of asemiconductor device 20. FIG. 36 is a flowchart showing a method ofmanufacturing the non-leaded type semiconductor device, i.e., QFNaccording to the first embodiment. The semiconductor device 20 ismanufactured through respective process steps of Steps 101 through 106.

Namely, after the starting of work, the semiconductor device 20 ismanufactured through respective steps of chip bonding (S101), wirebonding (S102), molding (S103), plating (S104), and pinch-cut (S105) andlead tip cutting (S106) by composite cut molding, and its work is ended.

Upon the manufacture of the semiconductor device 20 according to thefirst embodiment, such a matrix-configured lead frame 1 as shown in FIG.9 is prepared. The lead frame 1 is configured in such a manner that unitlead frame patterns 6 are arranged with 4 rows along an X direction andwith 14 columns along a Y direction. Fifty-six semiconductor devices 20can be fabricated from one sheet of lead frame 1. Guide hole lands 35 athrough 35 d used to transfer and position or locate the lead frame 1are provided on both sides of the lead frame 1.

Upon a transfer mold, runners are located between the respective rows.Thus, ejector pin holes 36 through which ejector pins are capable ofextending, are provided to separate a runner cured resin from the leadframe 1. In order to separate a gate cured resin cured at a gateportion, which branches off the runners and flows into its correspondingcavity, from the lead frame 1, ejector pin holes 37 through the whichejector pins are capable of extending, are provided.

FIG. 10 is a plan view showing a unit lead frame pattern 6. The unitlead frame pattern 6 is formed as a pattern having a frame portion 2shaped in the form of a rectangular frame, a plurality of leads 3extending inwardly from inside the respective sides of the frame portion2, and tub-suspension leads 4 which respectively extend inwardly of theframe portion from the four corners of the frame portion 2 and support acentral tub 25. The frame portion 2 has slits 38 intermittently providedat their sides in their side directions. Thus, the respective portionsof the frame portion 2 for supporting the leads 3 can be changedelastically.

A frame-portion corner (cornered portion) of the tub-suspension lead 4,which faces the ejector pin hole 37, is defined as a point where a gate(G) is located. Other three corners of the frame portion 2 are definedas air vents (E) are located.

FIG. 14 is a diagram showing the unit lead frame pattern 6 and a recessdefined in a parting face of one mold of a mold die. A square portionhaving such edges as to cross portions lying in the course of the leads3 is a cavity 40 for forming the package 5. Small rectangular portionsof the upper right, lower right and lower left corners of the frameportion 2 correspond to air vent grooves 41, and the upper left cornerof the frame portion 2 corresponds to a gate groove 42. A runner grooveor trench 43 is provided along the left side of the frame portion 2. Anejector pin hole 36 is provided in the central portion of the width ofthe runner groove 42.

No groove for the air vent is provided in an area for a length (b)between the cavity 40 and each air vent groove 41. Air vent areas 44 arerespectively formed by areas surrounded by the tub-suspension leads 4 atportions including the areas for the lengths (b), the adjacent leads 3and the frame portions. An inner end of each air vent groove 41 overlapswith its corresponding air vent area 44. Thus, air, which flows out fromthe cavity 40, flows into each air vent groove 41 through such air ventarea 44.

No groove for the gate is provided in an area for a length (a) betweenthe cavity 40 and the gate groove 42. Air vent areas 45 are formed byareas surrounded by the tub-suspension lead 4 at portions including thearea for the length (a), the adjacent leads 3 and the frame portions. Aninner end of the gate groove 42 overlaps with its corresponding gateareas 45. Thus, a resin, which flows into the gate groove 42, flows intothe cavity 40 through such gate areas 45.

Further, the tub-suspension leads 4 are stepwise bent by one stage inthe course thereof to elevate or lift the tub 25 upwardly.

The semiconductor device 20 is fabricated using such a lead frame 1.Namely, as shown in FIG. 11, a semiconductor chip 27 is fixed onto itscorresponding tub 25 through an unillustrated bonding material (chipbonding: S101). Electrodes 46 of the semiconductor chip 27 and theircorresponding inner ends of leads 3 are electrically connected to oneanother by means of conductive wires 28 (wire bonding: S102).

Next, the lead frame 1 whose assembly has been finished, is single-sidedmolded to form a package 5 (mold: S103). The single-sided molding iscarried out by a transfer mold device. Referring to FIG. 13, the leadframe 1 in which the chip bonding and the wire bonding have beencompleted, is clamped onto a mold die 50 comprising a lower mold 51 andan upper mold 52 of the transfer mold device.

As shown in FIG. 13, a parting face 52 a of the upper mold 52 becomesflat and hence one surface of the lead frame 1 is closely bonded to theparting face 52 a. As described above, a cavity 40 for forming thepackage 5, and an unillustrated runner groove, a gate groove 42 and anair vent groove 41 for guiding a resin melted in the cavity 40 areprovided in a parting face 51 a of the lower mold 51.

In the parting face 51 a of the lower mold 51, the circumference of theperiphery of the cavity 40 has a face 53 recessed by the same size asthe thickness of the lead frame 1, i.e., the thickness of each of theleads 3 and the tub-suspension leads 4. Thus, the leads 3 andtub-suspension leads 4 are clamped onto the lower mold 51 and the uppermold 52 by the recessed face 53 and the parting face 52 a of the uppermold 52 in a closely contact state. Thus, the tub 25 and thesemiconductor chip 27 are kept in a floating state at the middle stageof the cavity 40.

By feeding a molten resin 55 via the runner groove and the gate groove42, the resin 55 flows into the cavity 40 through a gate area 45. Airlying within the cavity 40 enters each air vent groove 41 through an airvent area 44 and escape from the cavity 40. With the escaping of suchair therefrom, the resin 55 also enters into the air vent areas 44 andthe air vent grooves 41.

Accordingly, the resin lying within the mold die 50 is cured accordingto the following resin cure processing (curing process). FIG. 12 is adiagram of a resin cured portion as viewed in a mold-opened state of themold die 50.

As shown in FIG. 12, the package 5 is formed in the center of the unitlead frame pattern 6. A runner cured resin 10 formed within itscorresponding runner groove by curing exists on the left side of thepackage 5. A gate cured resin 7 formed within its corresponding gategroove 42 by curing exists on the left side. Air vent resins 9 formedwithin their corresponding air vent grooves 41 formed on the extensionsof the upper right, lower right and lower left cornered portions of thepackage 5 exist.

In FIG. 12, portions to which dots (matt spots) are applied,respectively correspond to resin portions, i.e., resin burrs 11 eachhaving the same thickness as each of the leads 3, the tub-suspensionleads 4 and the frame portion 2. The gate areas 45 and air vent areas 44exist on both sides of the four-cornered tub-suspension leads 4 of thepackage 5. The gate cured resins 7 and the air vent cured resins 9 areformed inside their areas.

Next, a plating process is carried out (S104). The plating process isused upon implementation of the semiconductor device 20. Although notillustrated in the drawing, for example, a thickness of about 20 μm toabout 30 μm is formed on the surface of each of the leads 3 and thetub-suspension leads 4, which is exposed to the mounting surface 21 ofthe package 5.

Next, as shown in FIG. 16, pinch-cut (S105) and lead tip cutting (S106)are carried out by a press machine. The pinch-cut (the cutting offour-cornered tub-suspension leads 4) and the lead tip cutting (thecutting of leads extending in the X/Y directions) are carried out by acomposite cut mold attached to the press machine.

The pinch-cut is as follows. As shown in FIG. 16, a lead frame 1 isclamped between a die 15 a and a stripper 60 a. Four-corneredtub-suspension leads 4 and a gate cured resin 7 extended to both sidesof the tub-suspension lead 4, and air vent cured resins 9 arerespectively cut by die-punching using punches 16 a. The cut pieces 61 adrop in spatial portions of the die 15 a and are collected at apredetermined place by means of forced exhaust based on vacuumabsorption or the like.

Thus, the formation of the gate areas 45 and the air vent areas 44, eachof which falls within the thickness of each lead, makes it possible toensure an area to apply a die to lead surfaces on the package side andcut them from the mounting surface side of the leads by the punches. Thegate cured resins 7, which remain upon breaking and removal of the gatecured resins 7, are assuredly held in the spatial portions of thepinch-cutting die 15 a even if they have variations in size to someextent. Therefore, the dies and punches at the cutting lose no stabilitydue to the remaining gate cured resins 7.

FIG. 17 is a typical plan view showing dies 15 a and punches 16 a. FIG.15 is a plan view showing a lead frame in which a tub-suspension lead 4and gate cured resins 7 placed on both sides of the tub-suspension lead4, and tub-suspension leads 4 and air vent cured resins 9 placed on bothsides of the tub-suspension leads 4 are cut.

FIG. 18 is a diagram showing a state in which a tub-suspension lead 4and gate cured resins 7 located on both sides of the tub-suspension lead4 are cut by a die 15 a an a punch 16 a. At cut portions of thetub-suspension leads 4 at the base of the package 5, as shown in FIG.18, the gate cured resins 7 are formed in a space surrounded by thetub-suspension leads 4, the leads 3 located on both side of thetub-suspension leads 4, and the frame portion 2 with the same thicknessof each of the frame portion 2, tub-suspension leads 4 and leads 3.

Since the obverse and reverse sides of each gate cured resin 7 are flushwith the front and back of each of the leads 3 and the tub-suspensionleads 4 or the like and are protected and flattened, the occurrence ofresin waste can extremely be reduced. Since the gate cured resins 7 arecut in a state of being protected by the frame portion 2, the leads 3and the tub-suspension leads 4, a resin crack is not produced and doesnot extend deep within the package 5. Accordingly, moisture resistanceof the package is also improved.

The lead tip cutting is divided into two process steps of X-directionlead cutting and a Y-direction lead cutting in the case of composite cutmolding. Namely, the X-direction lead cutting is carried out as shown inFIG. 20. A lead frame is clamped between a die 15 b and a stripper 60 band each lead 3 extending along the X direction is punched out bypunches 16 b. Patterns for the die 15 b and the punches 16 b are formedas shown in FIG. 21. The punched-out lead frame 1 is formed as shown inFIG. 19. Further, cut pieces 61 b drop into a spatial portion defined inthe die 15 b and are thereafter collected at a predetermined location bymeans of forced exhaust based on vacuum absorption or the like.

The Y-direction lead cutting is carried out as shown in FIG. 23. A leadframe 1 is clamped between a die 15 c and a stripper 60 c, and leads 3extending along the Y direction are punched out by means of punches 16c. Patterns for the die 15 c and the punches 16 c are formed as shown inFIG. 24. The punched-out lead frame 1 is formed as shown in FIG. 22. Apackage 5 at this stage is cut and separated from a frame portion 2 ofthe lead frame 1, so that a non-leaded type semiconductor device (QFN)20 is fabricated. Cut pieces 61 c drop into a spatial portion defined inthe die 15 c and are collected at a predetermined place by means offorced exhaust based on vacuum absorption or the like.

The pinch-cut and lead tip cutting are carried out at the base of thepackage 5. For example, protruding lengths of the leads 3 and thetub-suspension leads 4 become 0.1 mm or less. Even in this case, theleading lines of the leads 3 and tub-suspension leads 4, and the cutlines of resin burrs 11, gate cured resins 7 and air vent cured resins 9linearly extend without being brought into irregularities respectively.

FIG. 25 is a cross-sectional view showing another semiconductor device20 fabricated by using a flat lead frame in which leads 3, a tub 25 andtub-suspension leads 4 are placed on the same plane. FIG. 26 is a bottomview of another semiconductor device. In such a structure, the tub 25and the tub-suspension leads 4 are exposed to a mounting surface 21 of apackage 5 in their entirety. Therefore, when it is fixed to a mountingor printed board such as a wiring board, the exposed surfaces of tub 25and tub-suspension leads 4 serve as heat dissipation surfaces and henceit is of practical use that the heat of the semiconductor chip 27 can bedissipated outside the package 5 rapidly. As a result, the semiconductordevice 20 can stably be operated.

When a plating film is provided on the surface of a lead frame in a leadframe state, the plating process shown in the flowchart shown in FIG. 8becomes unnecessary.

According to the first embodiment, the following advantageous effectsare brought about.

(1) The cutting of leads 3 and tub-suspension leads 4 that protrude fromthe periphery of a package 5, and the cutting of gate cured resins 7 andair vent cured resins 9 produced upon the formation of the package 5 areperformed while a die and punches are being applied to portionsrespectively identical in thickness and whose front and back are flat.Thus, they can be cut by punches and a die without partly applying anon-cutting stress on the gate cured resins 7 and air vent cured resins 9in a large way. It is therefore possible to reduce the occurrence ofresin waste 17 to a large extent as compared with the conventionalcutting method.

(2) According to the above (1), since the resin waste 17 can beprevented from occurring, the attachment and crimping of the resin waste17 to lead surfaces serving as external electrode terminals due to thespattering of the resin waste 17, and the occurrence of flaws caused bythe crimping can be restrained. It is also possible to ensuresolderability at mounting and enhance mounting yields. Furthermore, thereliability of the mounting of a non-leaded type semiconductor device 20can be improved.

(3) According to the above (2), since a matrix type lead frame takes astructure wherein unit lead frame patterns 6 are vertically andhorizontally arranged in line, the prevention of the spattering of theresin waste 17 results in the prevention of contamination of the resinwaste 17 on each unit lead frame pattern 6 around a predetermined unitlead frame pattern 6, whereby production yields can be improved to agreat extent.

(4) According to the above (1), since the occurrence of the resin waste17 can be restrained, the contamination caused by the cut-die resinwaste 17 can be prevented from occurring, and the availability factor ofa press machine for mounting a cut die can be improved.

(5) Since the gate cured resins 7 and air vent cured resins 9 around thepackage 5 are respectively identical to resin burrs 11 in obverse andreverse sides, it is difficult to visually confirm the gate cured resin7 and air vent cured resins 9 on the periphery of the package 5 of thenon-leaded type semiconductor device 20. Thus, the semiconductor deviceis look good and preferable even in outer appearance, and increases incommodity property.

(6) The cutting of leads 3 and tub-suspension leads 4 that protrude fromthe periphery of a package 5, and the cutting of gate cured resins 7 andair vent cured resins 9 produced upon the formation of the package 5 areperformed at portions respectively identical in thickness and whosefront and back are flat. Thus, they can be cut by punches and a diewithout partly applying an on-cutting stress on the gate cured resins 7and air vent cured resins 9 in a large way. Therefore, such a resincrack as to extend toward the inside of the package 5 is not produced.As a result, no moisture enters the package 5 through the resin crack.Further, the package 5 increases in moisture resistance, and productionyields are enhanced.

(7) According to the above (2) through (4) and (6), the manufacturingcost of a semiconductor device can be reduced in terms of highproductivity and an improvement in yield. For example, the yield isimproved about 0.5%.

Second Embodiment

FIGS. 27 through 29 are respectively diagrams showing a method ofmanufacturing a semiconductor device according to another embodiment(second embodiment) of the present invention, wherein FIG. 27 is atypical cross-sectional view showing a transfer mold state, FIG. 28 is atypical plan view showing a single-sided molded lead frame, and FIG. 29is a typical cross-sectional view showing a state in which gate curedresins, air vent cured resins and tub-suspension leads overlapping withthese are cut.

The second embodiment is different from the first embodiment in that asshown in FIG. 27, a gate 70 having a width d and air vents 71 eachhaving a width e are provided even on tub-suspension leads 4 at a resininjection place (G) and air vent places (E) corresponding to respectivecorners of a frame portion 2. The thickness of each of the gate 70 andthe air vents 71 is made thinner by about f than the thickness of eachof leads 3 and the tub-suspension leads 4. The thickness f ranges fromabout 20 μm to about 30 μm, for example, and serves as a flat surface.

Incidentally, the gate 70 and the air vents 71 may differ in groovedepth. In this case, the bottom of each groove is made flat so as not tocause resin waste in a subsequent step.

The gate 70 is wider than the width of each tub-suspension lead 4, andoverlaps with a gate area 45 on both sides of the tub-suspension leads 4and is in communication therewith. Further, each of the air vents 71 iswider than the width of the tub-suspension lead 4, and overlaps with itscorresponding air vent area 44 on both sides of the tub-suspension leads4 and is in communication therewith. As a result, a gate cured resin 7 ahaving a width d is formed between a package 5 and a gate cured resin 7in a state of a post-transfer mold lead frame 1 as shown in FIG. 28.Further, air vent cured resins 9 a each having a width e arerespectively formed between the package 5 and air vent cured resins 9.

The cutting of the gate cured resin 7 a and the tub-suspension lead 4superposed thereon, and the cutting of the air vent cured resins 9 a andthe tub-suspension leads 4 superposed thereon are carried out by a die15 a and punches 16 a as shown in FIG. 29 in a manner similar to thefirst embodiment.

Since portions of the gate cured resin 7 a and the air vent cured resins9 a, which make contact with the die 15 a and are supported thereby, areflat even in the case of such cutting, it is hard to cause resin wasteand a resin crack in a manner similar to the first embodiment.

Incidentally, the gate width d and the air vent widths e may be setlarger than the width of each tub-suspension lead 4 and connected to thegate area 45 and the air vent areas 44 to thereby less reduce resistanceat resin injection.

Incidentally, the alignment of the heights of the gate cured resin 7 aand the air vent cured resins 9 a formed on the four-corneredtub-suspension leads 4 makes it possible to carry out pinch-cut stabler.

It is possible to prevent the occurrence of the resin waste and theresin crack and achieve an improvement in yield even in the case of thesecond embodiment in a manner similar to the first embodiment.

Third Embodiment

FIG. 30 is a typical plan view showing a lead frame portion single-sidedmolded by a method of manufacturing a semiconductor device according toa further embodiment (third embodiment) of the present invention. Thepresent invention is a method of avoiding the superimposition of a gateand air vents on tub-suspension leads 4. Namely, in FIG. 30(a), the gateis provided so as to intersect a frame portion 2 to thereby cause itsleading end to communicate with a gate region or area 45. Further, airvents are respectively provided so as to intersect the frame portion 2to thereby cause their leading ends to communicate with theircorresponding air vent regions or areas 44.

In FIG. 30(b), a gate is provided so as to cross or intersect a frameportion 2 to thereby cause its leading end to communicate with spacesdefined between tub-suspension leads 4 and leads 3 and spaces definedbetween the adjacent leads 3. Further, air vents are respectivelyprovided so as to intersect the frame portion 2 to thereby cause theirleading ends to communicate with spaces defined between theircorresponding tub-suspension leads 4 and leads 3 and spaces definedbetween their corresponding adjacent leads 3.

Thus, inner ends of a gate and air vents based on or related to groovesdefined in a parting surface of a mold die are respectively spacedpredetermined distances from edges of a cavity 40 for forming a package5. This spacing is provided in such a manner that spacing defined bysurfaces of upper and lower molds of the mold die, which are flush withthe obverse and reverse sides of the leads 3 and tub-suspension leads 4,and side faces of the adjacent leads 3 or side faces of the leads 3 andtub-suspension leads 4 is used as a resin flow path.

It is possible to prevent the occurrence of resin waste and a resincrack and achieve an improvement in yield even in the case of the thirdembodiment in a manner similar to the first embodiment. Incidentally,the layout of the gate and the air vents is not limited to ones shown inFIG. 30.

While the invention made above by the present inventors has beendescribed specifically by the illustrated embodiments, the presentinvention is not limited to the above-described embodiments. It isneedless to say that various changes can be made thereto within thescope not departing from the substance thereof. For instance, thepresent invention can similarly be applied even to an SON wherein leadsused as external electrode terminals are exposed to both sides of amounting surface of a package, and a similar effect can be broughtabout. The present invention can be applied to at least the non-leadedtype semiconductor device.

In the present invention, the adoption of a sheet mold method makes itpossible to more suitably set an exposed shape of each electrode on theback of a package. The present sheet mold method is the technology of,when a lead frame is interposed between an upper mold and a lower mold,interposing a flexible resin sheet between the lower mold and the leadframe, and sealing each electrode portion of the lead frame inparticular with a resin by means of a clamping or pinch-holding force ofa die in a state in which the electrode portion has been cut into thesheet, thereby offsetting the back of the package with respect to amounting surface of the electrode. When such a method is adopted, theback of the gate cured resin 7 is also offset from the back of eachlead. Therefore, when the sheet mold method is applied to theembodiments of the present invention, the thickness of the gate curedresin might be smaller than that of the lead frame.

While the present embodiment has described the structure wherein thetub-suspension leads 4 are exposed from the corners of the package, theinvention is not limited to such a type that the tub-suspension leads 4are exposed at the package corners. The invention may be applied to, forexample, a case where the tub-suspension leads 4 are not provided, and acase where the tub-suspension leads 4 are formed at portions other thanthe corners. In this case, the gate region or area 45 may be providedbetween the adjacent external electrode terminals (leads).

Advantageous effects obtained by typical ones of the inventionsdisclosed in the present application will be described in brief asfollows:

(1) Since the occurrence of resin waste and a resin crack can berestrained when a gate cured resin and air vent cured resins employed inthe manufacture of a non-leaded type semiconductor device are cut, animprovement in production yield and an improvement in the quality of aproduct can be achieved.

(2) Since the occurrence of resin waste and a resin crack can berestrained when a gate cured resin and air vent cured resins employed inthe manufacture of a non-leaded type semiconductor device are cut, it ispossible to prevent a reduction in availability factor of a cuttingdevice or the like due to the resin waste and reduce the manufacturingcost of the semiconductor device.

What is claimed is:
 1. A semiconductor device comprising: anencapsulater including an insulating resin, a tub, first leads andtub-suspension leads exposed to a mounting surface of said encapsulater,and a gate cured resin and air vent cured resins which remain as aresult of formation of said encapsulater and which protrude from saidencapsulater; and a semiconductor chip sealed in said encapsulater andbonded on said tub, a plurality of said first leads being electricallyconnected to said semiconductor chip and said tub-suspension leads beingjoined to said tub; wherein each of said gate cured resin and said airvent cured resins exists in a portion between a respectivetub-suspension lead and a respective first lead with a thicknessidentical to or smaller than a thickness of each of resin burrs.
 2. Asemiconductor device comprising: an encapsulater including an insulatingresin, a tub, first leads and tub-suspension leads exposed to a mountingsurface of said encapsulater, and a gate cured resin and air vent curedresins which remain as a result of formation of said encapsulater andwhich protrude from said encapsulater; and a semiconductor chip sealedin said encapsulater and bonded on said tub, a plurality of said firstleads being electrically connected to said semiconductor chip and saidtub-suspension leads being joined to said tub; wherein said gate curedresin and said air vent cured respectively extend from edges of saidencapsulater with a predetermined thickness and have obverse and reversesides formed as flat surfaces.
 3. The semiconductor device according toclaim 2, wherein said gate cured resin partly overlaps with therespective tub-suspension lead.
 4. The semiconductor device according toclaim 2, wherein said air vent cured resins partly overlap withrespective tub-suspension leads.
 5. The semiconductor device accordingto claim 2, wherein said gate cured resin partly overlaps with at leastone first lead.
 6. The semiconductor device according to claim 2,wherein each of said air vent cured resins partly overlaps with at leastone first lead.